The present invention relates to a valve which controls the fuel level, the venting and traps fuel vapors from an automotive vehicle fuel tank to a fuel canister, or the like, and which prevents escape of liquid fuel from the fuel tank in the event of rollover of the vehicle.
A fill limit control valve, which is normally disposed in a vehicle fuel tank, frequently comprises a housing having a valve portion for sealing engagement about a hole in a fuel tank and a float portion extending into the fuel tank. The type of valve to which the subject invention pertains responds to the level of liquid fuel in the fuel tank, staying open to vent vapor as long as the fuel level is below a predetermined level. These are sometimes referred to as xe2x80x9cfill controlxe2x80x9d or xe2x80x9cshutoffxe2x80x9d valves, since closing thereof creates a sudden pressure increase in the tank thereby preventing further refueling.
The valve portion defines a vent opening for venting vapors from the fuel tank and a vapor outlet for conveying fuel vapors to a vapor canister. A float is movably supported by the float portion for seating against and closing the vent opening in response to the float rising to a predetermined fuel level. Examples of such prior art assemblies are shown in U.S. Pat. Nos. 5,590,697 to Benj ey et al. and U.S. Pat. No. 5,860,458 to Benjey et al.
Sometimes these valves are supplemented with a gravity-responsive rollover device supported at the bottom of the float portion for engaging and moving the float upwardly to seal the vent opening in response to a predetermined amount of deviation from vertical, e.g., a rollover. An example of such a prior art assembly is shown in U.S. Pat. No. 5,809,976 to Cook et al.
Although all of these assemblies may perform satisfactorily, liquid fuel may inadvertently pass through the valve and into the vapor canister. Influx of liquid into the vapor canister, can prematurely saturate the canister and pollute the environment. Hence, there remains a need to reduce and virtually eliminate the amount of liquid fuel that passes out of the valve during normal operation.
The disadvantages of the prior art may be overcome by providing a fill limit control valve assembly disposed in a vehicle fuel tank. The fill limit control valve assembly has a housing having a valve portion for connection to a fuel tank and a float portion for extending into the fuel tank. The valve portion defines a vent opening for venting vapors from the fuel tank. A float is movably supported by the float portion for movement between an open position spaced from the vent opening and a closed position seating against and sealing the vent opening in response to the float rising to a predetermined fuel level. A liquid fuel trap is disposed above the vent opening to limit liquid fuel flow through the vapor outlet.
Accordingly, the subject invention provides a fill limit control valve that mininmizes and virtually eliminates the undesirable flow of liquid fuel into a vapor canister. Hence, only fuel vapors pass through the valve and into the canister.
According to another aspect of the invention, there is provided a fill limit control valve assembly having a float which traps vapor during normal fuel filling to enable the float to become buoyant and responsively move to a closed position and which collects liquid fuel when in an inverted rollover condition to prevent buoyancy and responsively move to the closed position.